Safety appliance for automatic hammers.



S. W. MORROW.

SAFETY APPLIANCE FOR AUTOMATIC HAMMERS.

APPLICATION FILED AUG.30. 1917.

1,269,729. Patented June 18, 1918.

- :TEATTETTAGHTA \v i" UNITED STATES PATENT SAMUEL WILSON MORBOW, OF BALTIMORE, MARYLAND, ASSIGNOR TO U. S. SAFETY APPLIANCE COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION OF MARY- LAND.

SAFETY APPLIANCE FOB AUTOMATIC HAMMERS.

Application filed August 30, 1917.

To all whom it may concern Be it known that I, SAMUEL WILSON Monnow, a citizen of the United States of America, residing in the city of Baltimore, State of Maryland, have invented certain new and useful Improvements in Safety Appliances for Automatic Hammers, of which the following is a specification.

This invention relates to a safety device for pneumatic or similar hammers for use with a snap or set which may be a riveter, a chisel or any tool adapted to be actuated by the blows of the hammer, and is an improvement on the device of U. S. Patent No. 1,206,511, the property of the assignee of this application. The invention in this application as in the previous patent, relates to means for locking the thimble which holds the snap or set and prevents it from being shot out of the barrel when not in contact with the work.

.In both instances, the thimble is held by a transverse key in slots extending through the thimble into the body of the tool. The key and slots have their operative surfaces at right angles to the direction of recipr0 cation of the hammer. While the direction of these surfaces would, according to the theory of mechanics, give no resultant force at right angles to the direction of reciprocation of the hammer, there is a very perceptible vibration of the key tending to throw it out of its seat at each blow of the hammer. Owing to the frequency and sharpness of the blows, the strain on the spring which in the patented device extends along the barrel at right angles to the key, is very considerable and tends 'to shorten the life of the safety appliance by breaking the lug at the point where the spring is attached to the barrel, or even breaking the spring. This effect is most noticeable in the larger and heavier sizes of the hammer where the vibration due to the shock of the hammer against the tool is much more considerable and the tendency of the key to fly out of its seat is greater. The stress on the spring in the patented device is partly due to the necessity for fastening it to the key.

In the improved form, I use a plurality of laminated springs which encircle the bar rel, placing them in a position transverse to the direction of reciprocation of the tool. These springs are so placed that they merely press on the keys and serveto keep them in Specification of Letters Patent.

Patented June 18, 1918.

Serial No. 188,915.

the slots in both the thimble and barrel,

acting in a way as shock absorbers in that they yield to, take up and reduce the vibration in a direction transverse to the stroke of the hammer but do not have any tendency to rock or vibrate in the direction of the stroke of the hammer as they are entirely free of attachment to the keys. For convenience when the thimble is removed, the keys are so arranged that they cannot pass through the slots in the thimble from which they project into the slots in the barrel, but are held in position in the slots by the springs which in the form of the invention shown are mounted in two sets, the springs of each set bearing on the adjacent ends of both ke s holding them so that in the preferred orm they cannot be removed without removing one or the other of the springs.

In the accompanying drawing, I have illustrated my invention in its preferred form, the same being applied to a pneumatic hammer.

Figure 1 is an elevation of the hammer;

Fig. 2 is a section on the line 2, 2 of Fig. 1; a

Fig. 3 is a longitudinal section on the line 3, 3 of Fig. 2; v

Fig. 4: is a longitudinal central section through the thimble; and

Fig. 5 is an elevation of the same.

Referring to the drawings by numerals, the hammer is of the usual or any preferred type having a barrel 1, a grip 2, and a thimble 3 for holding the set 4. The thimble has an internal shoulder 5 surrounding the opening in the lower end at 6 which is concentric with the axis. The set or snap 4 protrudes through the opening, the shoulder 5 beingengaged by an external shoulder 7 on the set. So long as the thimble is in position, the tool cannot escape. The thimble is held, in the form of the invention shown, by a plurality of keys 8 engaging transverse slots 9 in the barrel and corresponding slots 10 in the thimble and projecting through them into the slots 9 in the barrel. This is most clearly illustrated in Fig. 2 which shows the slots 10 having their end surfaces disposed in radial planes of the barrel, giving an opening which tapers toward the center of the barrel so that the key which is correspondingly shaped can be inserted from without but when held by the spring pres sure which is also from without, cannot be forced through the slot into the central cavity of the barrel. The springs 11 are mounted each on the thimble in a circumferential groove 12 which serves to guide the springs and prevent displacement. These springs which are preferably laminated and stepped, that is, the outer one is the shorter and the successive layers each a little longer than the preceding, are held in position by a central pin or bolt 13 in the center of the spring and half wa between the slots 10.so that as has already een pointed out, the end of each spring bears on the corresponding end of thekeys. The keys as shown are two in number, a. e., equal to the number of sets of springs, but the number may of course be varied.

By reference to the drawing, Fig. 2, it will be noted that the transverse slots 9 in the barrel are fiat centrally at 14 and inclined at the ends at 15 and the inner surfaces of the keys are correspondingly shaped; also the inner edge of the key is curved or sloped as shown at 16 in Fig. 3. The incline makes it possible to force the keys out of the slots in the barrel, thus removmg the thimble b rotating the key, the surfaces 14 and 15 siding over the corresponding surfaces of the slot until the key is" out on the cylindrical surface of the barrel. The lateral curvature of the keys at 15 makes it possible to pass the thimble over the end of the barrel forcing the keys outward by contact of the curved surfaces with the correspondingly curved and inclined surfaces 16, 17 of the end of the barrel, and then permatting it to drop into the slot 9 provided for that purpose. As already pointed out in this case and shown in the previous patent, the stop surfaces 18, 19 are flat and transverse to the direction of reciprocation ofthe hammer.

In setting up the tool, the keys 8 are placed in the slots 10in the thimble and the laminated s rings fastened in osition with each spring earmg on the a jacent portion of the keys, the springs being seated in the circumferential groove 12 in'the thimble provided for that purpose. When thus assembled, the thimble is complete and none of the parts can be lost or displaced. The keys cannot be gotten out of the grooves without removing the springs, as already pointed out. Next t e set or tool is inserted in the thimble. If the shoulder 7 is, asv in the present instance, too large to clear the keys, they are easily pushed out suificiently to permit it to pass owing to the cam action of the curved or inclined surfaces 16.' Next the thimble with the set is applied to the barrel, the set being inserted in the opening 20 in the-barrel while the thimble is passed over the barrel, the curved surfaces 16 engaging the correspondingly curved and reduced end of the barrel 21 serving to open the keys and weaves force them. out sufficiently to ermit the entrance of the barrel into the thnnble. As soon as the keys come in re 'stration with the slots 9 in the barrel, they rop into place, fastening the thimble sothat it cannot be removed except by rotating the thimble on the barrel to release the keys by the action of the inclined surfaces 14 and 15, see par ticularly Fig. 2.

By the combination of arcuate laminated springs and transverse keys as illustrated particularly in Fi 2, I avoid undue strain on the springs an the intensity of the vibration, producing a stronger and more effective apparatus as compared to the previous product.

I have thus described a single embodiment of my invention specifically and'in detail in order that the nature and. operation of the device may be fully understood; however, the specific terms herein are used descriptively rather than in their limiting sense, the minor details being capable of variation and substitution, and the scope of the invention is defined in the claims.

What I claim and desire to secure by Letters Patent is:

1. In a pneumatic hammer having a barrel, a shouldered set, a thimble with a cooperating shoulder to prevent escape of the set from the socket, means for holding the thimble consisting. of a plurality of trans-' verse keys, transverse slots in the thimble and registering slots in the barrel, and leaf.

springspartially encircling the thimble between the slots and bearing at each side of at the same time reduce f their centers on the adjacent keys, the slots and keys having cooperatin stop-surfaces transverse to the direction 0 reciprocation of the hammer.

2. In a pneumatic hammer, a thimble to prevent escape of the set from its socket, means for holding the thimble consisting of a plurality of transverse keys, slots in the thimble in which the keys are seated, regisextend, leaf-springs extending in a trans verse direction, each spring bearing at each side of its center on the adjacent end portions of the keys, and means for fastening the springs to the thimble between the keys,

tering slots in the barrel into which the keys the slots and keys having stop surfaces at right angles to the direction of reciprocation of the hammer.

3. In a pneumatic hammer, a thimble to prevent escape of the set from its socket means for holding the thimble consisting of a plurality of transverse keys, slots in. the thimble in which the keys are seated registering slots in the barrel into which the keys extend, leaf springs extending partially around the thimble in a transverse direction, each spring bearing on the adjacent ends of the keys, means for fastening the springs to the thimble between the keys, the

slots and keys having stop surfaces at right angles to the direction of reciprocation of the hammer. a circumferential groove in the thimble to guide the springs, the key slots being in the groove.

4. In combination with a pneumatic hammer, a thimble for holding the set, transverse keys, transverse slots in the thimble and barrel of the hammer to receive the keys, the slots in the thimble being shaped so that the keys protrude inwardly into the slots in the barrel but cannot pass through the slots in the thimble, transversely extending leaf springs, and means for securing them between the ends of the keys, the leaf springs bearing at each end on the keys near the adjacent ends.

5. In combination with a pneumatic hammer, a thimble to hold the set, transverse keys, slots in the thimble and in the barrel to receive the keys, the thimble having a circumferential groove in which the slots are located, a transverse spring bearing at each end on the adjacent ends of the keys, and means securing the spring between the keys, the spring being located in the groove which serves as a guide for the spring, the slots and keys having flat stop surfaces at right angles to the direction of reciprocation of the hammer.

Signed by me at Baltimore, Maryland, this 28th day of August, 1917.

SAMUEL WILSON MORROW. Vitnesses:

JAMES F. JoHNsoN, BURNHARD J. Rims. 

